Natural and sexual selection in a wild insect population

要理解为什么动物种群的大小和分布会发生变化，以及为什么个体的行为会发生变化，就必须了解进化是如何发生的。在过去的几十年里，生态学研究的一个真正的成功案例是对哺乳动物和鸟类的长期研究，在这些研究中，有可能跟踪个体及其后代及其后代的后代等等。测量个体成功传递基因的能力使研究人员能够解决有关特定特征如何影响繁殖成功从而推动进化的问题。例如，对达尔文雀的研究已经能够证明进化的发生，因为特定的喙形在特定的气候条件下是有益的。我们建议将一个全新的领域系统添加到迄今为止在自然界中已经被彻底研究过的少数哺乳动物和鸟类中。我们将使用数字摄像机和麦克风网络来监测西班牙草地上单独标记的蟋蟀种群。在实验室里对蟋蟀进行了很好的研究，发现它们有复杂的性选择形式，雌性根据它们的叫声在雄性之间进行选择，雄性打架，雌性操纵来自几个雄性的精子来偏爱无关的雄性，等等。然而，尽管我们现在在实验室里对蟋蟀的行为和生理有了很多了解，但我们几乎不知道这些方面在现实世界中有多重要。这种差异令人担忧：实验室环境消除了一些在野生种群中可能非常重要的选择来源，并可能产生新的压力；例如，在实验室里，唱歌更大声的雄性可能会得到更多的配偶，但在野外，这样的雄性更有可能被鸟类吃掉。蟋蟀的这些问题几乎与所有其他模型系统一样：无一例外，在野外研究得很好的物种很难在实验室中研究（例如马鹿，大山雀），而在实验室中研究得很好的物种在野外研究得很差（例如果蝇，柄眼蝇）。我们迫切需要的是一个弥合这种鸿沟的系统。技术的进步意味着这样的研究现在是可能的。我们打算用80台摄像机来监控一小群蟋蟀的大部分活动：谁和谁交配，谁赢得了战斗，每只雄蟋蟀唱多少歌，每只蟋蟀活多久等等。这将与种群中每个成年个体的DNA样本相结合，这将使我们能够计算出每个个体在下一代成年个体中留下了多少后代。基于我们的遗传标记的模拟表明，我们的谱系至少与教科书中使用的大型脊椎动物研究一样可靠。监测和亲子鉴定的结合将使我们能够解决进化生态学中的一些关键问题：雄性是否更依赖于交配能力而不是生存能力？2. 男性在繁殖成功率上是否比女性差异更大？3. 雄性交配成功是因为它们对雌性有吸引力还是因为它们善于与其他雄性打斗？4. 雄性在交配上付出了很多努力，是否付出了寿命较短的代价？5. 与有吸引力的雄性交配的雌性会生出更健康或更有吸引力的后代吗？6. 是否有一些基因对一种性别有益，但对另一种性别有害？7. 基于实验室的性状遗传估计与实地的估计相符吗？8. 有亲缘关系的昆虫会相遇吗？如果相遇了，它们会互相交配吗？在蟋蟀身上回答这些问题将提供跨物种的见解，并为现代生物学中心范式的有效性提供关键见解，即我们可以在实验室中研究行为生态学。

To understand why animal populations change in size and distribution and why individuals behave as they do, it is essential to understand how evolution occurs. Over the past few decades a real success story in the study of ecology has been the long-term studies of mammals and birds where it has been possible to follow individuals and their offspring and their offspring's offspring and so on. The ability to measure individual success in passing on their genes has enabled researchers to address questions about how particular traits affect reproductive success and hence drive evolution. For instance, studies of Darwin's finches have been able to demonstrate evolution occurring because particular beak shapes are beneficial under particular climatic conditions. We propose to add a completely new field system to the handful of mammals and birds which have thus far been thoroughly studied in nature. We will use a network of digital video cameras and microphones to monitor a population of individually marked field crickets in a Spanish meadow. Crickets have been well studied in the laboratory, revealing that they have complex forms of sexual selection whereby females choose between males according to their songs, males fight, females manipulate sperm from several males to favour unrelated males and so forth. However, although we now have many insights into the behaviour and physiology of crickets in the laboratory, we have almost no idea how important these various aspects are in the real world. This discrepancy is a source for concern: Laboratory situations remove some sources of selection that may be very important in wild populations and may create new pressures; for instance, it may be that males that sing louder get more mates in the lab, but in the field such males may be more likely to be eaten by birds. These issues with crickets are shared with almost all other model systems: without exception the species that are well studied in the field are too difficult to study in the lab (e.g. Red Deer, Great Tits), and the species that are well studied in the lab are poorly studied in the field (e.g. Fruit Flies, Stalk Eyed Flies). What is desperately needed is a system that bridges this divide. Advances in technology mean that such a study is now possible. We propose to use 80 cameras to monitor the majority of activity occurring in a small population of crickets: who mates with whom, who wins fights, how much each males sings, how long individuals live and so on. This will be combined with DNA sampling of every adult in the population which will allow us to work out how many offspring each individual leaves in the next generation of adults. Simulations based on our genetic markers show that our pedigree will be at least as reliable as those used in the text-book studies of large vertebrates. The combination of monitoring and parentage assignment will allow us to address some key questions in evolutionary ecology: 1. Do males depend more on their ability to get matings than their ability to survive? 2. Do males vary more in their reproductive success than females? 3. Is male mating success due to them being attractive to females or good at fighting with other males? 4. Do males that devote a lot of effort to getting matings pay a price in terms of shorter lifespan? 5. Do females that mate with attractive males have healthier or more attractive offspring? 6. Are there some genes that are beneficial for one sex but detrimental to the other? 7. Do lab based estimates of the inheritance of traits match estimates made in the field? 8. Do related insects ever meet and if they do, do they mate with one another? Answering these questions in crickets will provide insights across species and provide crucial insights into the validity of a central paradigm of modern biology which is that we can do behavioural ecology in the lab.